1. Field of the Invention
This invention relates to a numerical control system for a machine tool or the like and, more particularly, to a numerical control system for displaying, on the screen of a display unit, operation information entered by an operator's panel, and for performing numerical control on the basis of the displayed operation information.
2. Description of the Related Art
A numerical control unit executes predetermined numerical control processing on the basis of numerical control program data and operation information determined or set by an operator's panel. The operation information may include:
(1) mode information for specifying operating modes for editing, memory operation, tape operation, manual input operation, jog operation, handle feed operation and the like;
(2) single block on/off information;
(3) dry run on/off information;
(4) block delete on/off information;
(5) machine lock on/off information;
(6) feed hold on/off information;
(7) reference point return on/off information;
(8) jog feed direction information;
(9) jog feed velocity and overdrive information;
(10) handle axis selection information; and
(11) handle feed magnification information.
In the prior art, all these items of operation information are fed into the numerical control unit by setting switches, or by pressing buttons, which are provided on the operator's panel located on the machine side. However, such an arrangement results in a very large number of switches and buttons and makes operation a complicated matter. This invites operator error.
Accordingly, there has recently been proposed a numerical control system as shown in FIG. 1, in which a numerical control unit NC for numerically controlling a machine tool is provided with a numerical control operator's panel MDI, in addition to a machine operator's panel, as means for entering operation information. The necessary operation information is displayed on the screen of a display unit CRT of the numerical control operator's panel MDI, and desired operation information is selected and fed into the numerical control unit NC by operating keys or a light pen.
The method of setting and entering operation information in this numerical control system will now be described in conjunction with FIGS. 2 through 5.
FIGS. 2(A) and 2(B) are examples in which operation information is displayed on the screen of the display unit CRT of the numerical control operator's panel MDI unit and the operation information is set and entered by operating keys or light pen connected to the numerical control operator's panel MDI while the display is being viewed.
In FIG. 2(A), "MODE" denotes a mode information selection line. The arrangement is such that any one operating mode can be selected from among a manual input operation (MDI), automatic operation (AUTO: tape or memory operation), editing operation (EDIT), handle operation (HNDL), jog feed operating (JOG) and zero-point return operation (ZRN). For example, to select automatic operation (AUTO), the operator manipulates a horizontal shift key and a vertical shift key to position a cursor ( ) to the left of AUTO. If this is done, the automatic operating mode will be selected. Further, "HANDLE AXIS" represents a handle feed axis selection line, "HANDLE *10" represents a handle feed magnification selection line, "RAPID OVRD" denotes a rapid-traverse override setting line, and "FEED OVRD" denotes a feed velocity override setting line. It should be noted that selection of operation information is performed as in the case of the mode selection. Specifically, desired operation information is selected by the operator positioning the cursor at the head of the item of the selection line being displayed on the screen of the display unit CRT of the numerical control operator's panel MDI. The setting of an operation quantity on each of the setting lines is performed by the operator operating a horizontal shift key to extend bar graphs SGl and SG2 to the right or left. That is, when the horizontal shift key is operated, the bar graph is elongated or contracted during operation of the key to set and display a quantity commensurate with the length of the bar graph. In FIG. 2(A), jog feed velocity (JOG FEED) is set to 20 mm/min, and feed override (FEED OVRD) is set to 100%.
In FIG. 2(B), "BLOCK DELETE" represents a block delete on/off selection line, "SINGLE BLOCK" a single block on/off selection line, "MACHINE LOCK" a machine lock on/off selection line, "DRY RUN" a dry run on/off selection line, "PROTECT KEY" a selection line for whether or not editing of data stored in memory is to be forbidden, and "FEED HOLD" a feed hold on/off selection line. The selection of operation information is performed by the operator positioning the cursor to the left of ON or OFF on each selection line. In the example of FIG. 2(B), the values block delete OFF, single block OFF, machine lock ON, protect key PROTECT and feed hold OFF have been set.
The foregoing is for a case where all operation information is entered using the screen of the display unit CRT. However, as shown in FIG. 3, an arrangement is permissible wherein the operation information is divided into a mode selection group [FIG. 3(A)], handle feed group [FIG. 3(B)], feed velocity related group [FIG. 3(C)], automatic operation related group [FIG. 3(D)], program protect group [FIG. 3(E)], feed hold group [FIG. 3(F)], and a jog feed related group (not shown), with only several of these groups being displayed on the screen of the display unit CRT and entered.
FIG. 4 is a view of an arrangement in which manual feed keys are provided on the numerical control operator's panel MDI. By operating keys K1 through K4, a machine tool or robot can be fed manually along a prescribed axis, and rapid traverse can be performed by operating a key K5 at the same time. Depending upon the machine tool, sometimes the axes of travel are the X and Y axes. For example, for a milling machine, the coordinate system is fixed as shown in FIG. 5(A), and for a lathe, the coordinate system is fixed as shown in FIG. 5(B). Accordingly, depending upon the machine tool used, the keys sometimes are for the +X axis, sometimes for the +Y axis and sometimes for the +Z axis.
In order to display the necessary operation information on the screen of the display unit CRT in the conventional numerical control operator's panel MDI, it is required that the operator's panel have input keys corresponding to various symbols. Specifically, the input keys necessary can include the letters of the alphabet, numerals, katakana (Japanese word symbols), upper and lower cases, percent (%), inequality symbols (&gt;, &lt;), space, etc. Although there are also instances where various symbols can be entered by the same key through use of a selection key, operation in this manner is troublesome because it is necessary to operate the selection key separately each time. Moreover, even though some symbols have a very low frequency of use, it is still necessary to provide the keys for these symbols. This increases the number of keys disposed on the operator's panel MDI, so the face of the operator's panel inevitably occupies a large space. Furthermore, the arrangement of the keys is complicated. This is undesirable in terms of both operability and appearance. In addition, there is the danger that the keys may be manipulated indiscriminately by an outsider, thereby resulting in erroneous operation.
Further, with the conventional numerical control system as shown in FIG. 1, the operator's panel on the machine side is provided with a mixture of operating members for controlling the machine tool through the numerical control unit NC and for controlling the machine tool directly without the intermediary of the numerical control unit NC. Consequently, the operator's panel on the machine side is complicated, invites erroneous operation and inevitably raises the cost of the numerical control system.